Service lets you point traffic at revisions it does not own #11916
Description
What version of Knative?
Repro'd with 0.25.1
Expected Behavior
Update the traffic rules of a Service to point to another revision should fail
Actual Behavior
The traffic rule is realized and hitting Service A will route traffic to a revision owned by a different Service
Steps to Reproduce the Problem
$ kn service create aaa --image gcr.io/knative-samples/helloworld-go --env TARGET=A
...
$ kn service create bbb --image gcr.io/knative-samples/helloworld-go --env TARGET=B
...
$ curl aaa.default
Hello A!
$ curl bbb.default
Hello B!
$ kn service update aaa --traffic bbb-00001=100
$ curl aaa.default
Hello B!